Prior magnetic structures for use in a magnetic separator typically utilize an arrangement wherein magnets alternate between a radially polarized direction and a direction perpendicular to the radius, commonly referred to as the azimuthal direction. Furthermore, a structure of low reluctance material is added to the rear of the magnetic structure to further decrease leakage flux and to increase the field in the vicinity of a working surface, past which the magnetic material and waste material pass.
Although these apparatus effectively control leakage flux, the field is nonuniform in the vicinity of the working surface. Specifically, portions of the magnetic field corresponding to decreased magnetic strength occur as the magnetic field is traversed.
It is desirable to provide a uniform field in the vicinity of the working surface and to also minimize leakage flux occurring behind the magnetic assembly. Furthermore, it is desirable to maximize the gradient of the radial component of the magnetic field because the force acting upon a particle within the field is proportional to this gradient. In this manner, the field strength increases quickly at the edges of the field, and hence fewer magnets need be employed to separate the magnetic product from the non-magnetic material.